Hunter Killer

The first part of the mission is easy. Just avoid the sea mines and follow the rest of the fireteam. Once the enemy vessel passes, you may approach the rear fin of the OSCAR II (same class as the Kursk which sunk in 2000) and place an explosive charge to make it surface.

Leave the enemies to your advance team and approach the sub's entry lock once the gunfire slackens. Once inside, you will be heavily out-numbered.

Have Frost follow Sandman down and be ready to take out the two Russians in the rear berths once Sandman opens the door. Firing past him is difficult, and if you don't do that as soon as the door opens, the first doorway becomes very hard to move past on Veteran (unless you want to use valuable flashbangs).

Head downstairs to the flooded engineering section and down the guy spraying the extinguisher. This will alert the other enemies, so you need to fire through the glass of the containment chamber to whack enemies who are visible.

Round the right corner carefully (or use a flashbang) and cack the remaining ass in the hallway. Before you approach the stairs leading up to the boiler room, reload fully so you can drill the two enemies who come down the stairs to check on the noise.

The next two rooms are nightmares on Veteran .... especially if you go around exploring, hence encouraging enemies to continually spawn in hidden spaces on the sub's sides. If you make your way slowly (but surely) to the white HUD marker, you will meet the minimum of enemies.

Stay on the lower deck in the first room, and go upstairs only once you reach the end of the second room. While this may put you in some danger against enemies from above, you don't need to worry about enemies attacking you from below.

Flashbang the second chamber; with the amount of enemies inside, you need an advantage to gain a foothold. Just watch out how your grenades roll, as the tight quarters can make the devices bounce back towards you. Get to the stairs leading to the bridge and wait for Sandman to catch up.

Take out the charging enemy upon breach, or he will kill you instantly. Down the rest of the enemies from right to left (or as you see fit). Before you insert the key into the control panel, reload your weapons -- you only need 30 rounds (or a fully loaded handgun) for the rest of the mission.

Meet Sandman at the missile control terminal and introduce the Russian navy to the OSCAR II's full payload of sub-to-ship missiles. Get the hell out via the conning tower ladder afterward.

At the top of the ladder, veer left and hit the SEAL Team Assault Boat (STAB). The key thing about Veteran is to keep towards the right (far away from the Russian minelayers/picket boats) or the incoming gunfire will kill you. Keep the buoys on your boat's left and follow the other STAB whilst staying to the right.

When the Russian minelayer rams your STAB, point your weapon towards the vessel's stern and open fire on the spherical pin mines to escape. Once you reach the fiery piers, you're practically home free. Drive into the Chinook's rear ramp and end the mission.